THERMAL INFRARED MAPPING OF WHITE-ISLAND VOLCANO, NEW-ZEALAND

The first aerial thermal infrared (TIR) survey of White Island volcano was successfully performed during the early morning of 15 April 1992. High spatial resolution (1-2 m) TIR imagery, representative of surfac e temperatures, and simultaneous visible video imagery were obtained o ver approximately 75% of the exposed portion of this active volcano. S urface temperatures, ranging from ambient (11.8 degrees C) to active ( 95.7 degrees C), were measured at 12 sites for image calibration purpo ses. The TIR imagery clearly depicts structurally complex thermal area s within Main Crater. Regions of thermal activity along the northern c rater rim and on the northwest, north and northeast crater flanks were also detected. One thermal seepage was observed on the north coast, w est of North East Point. A close correlation is demonstrated between t he TIR thermal anomalies and present vent locations, prehistoric subcr ater boundaries, and the geohydrology of the hydrothermal system hoste d in Main Crater. Most of the active 1978/90 Crater Complex was mapped as a high-temperature anomaly, except for one relatively cool area wh ich developed soon after by subsidence and collapse into a major new v ent, Princess Crater. Impermeable crater lake sediments are believed t o cap the hydrothermal system in parts of the central and eastern subc raters where the TIR map shows appreciable areas at ambient temperatur es. An area of high heat flow is located in the south side of the east ern subcrater where steam and gas escape through fractured lavas. The distribution of thermal anomalies in the eastern subcrater suggests th at there may have been two smaller craters located within the larger, now filled in, structure.